CuS-CdS@TiO2 multi-heterostructure-based photoelectrode for highly efficient photoelectrochemical water splitting

A three-dimensional hierarchical CuS-CdS@TiO2 multi-heterostructure has been fabricated as a highly promising photoanode for PEC water splitting. The CdS@TiO2 structure was synthesized by a two-step hydrothermal method, therein TiO2 nanorods (TiO2 NRs) were used as the template to grow the CdS branches (CdS BRs). Then the surface of the heterostructure was sequentially coated with a p-type CuS semiconductor via a simple SILAR method. The optimized CuS-CdS@TiO2 photoelectrode exhibits a remarkably high photocurrent density of 12.6 mA cm  2 at 1.23 V vs RHE under standard AM 1.5 light illumination. The enhancement in the PEC performance could attribute to the wide range of solar spectrum absorption in CdS BRs, which can generate more photo charge carriers. Meanwhile, the high conductivity of TiO2 NRs serves as an efficient pathway to transfer photogenerated electrons from the CdS BRs to the FTO substrate. In addition, the p-n junction formed between CuS and CdS@TiO2 heterostructure could improve the separation of electron-hole on the surface of the photoanode. This study demonstrates an efficient pathway to improve the photoelectrochemical performance of TiO2-based photoanodes.